Ordered mono and multilayer films built by the sequential deposition of organic monolayers from a water-gas interface, known as monolayer assemblies [K. B. Blodgett, J. Am. Chem. Soc., 57, 1007 (1935); K. B. Blodgett & I. Langmuir, Phys. Rev., 51, 964 (1937)], or Langmuir-Blodgett (LB) built-up films, have recently become the focus of intensive research aimed at developing novel applications of scientific and technological interest. LB films are considered promising in a wide range of applications, such as: preparation of artificial membranes, fabrication of passive and active ultrathin film components for novel microelectronic and optical devices, ultrathin photoresists, molecular films useful in solar energy conversion, etc. (see Proceedings of the First International Conference on Langmuir-Blodgett Films, Durham (1982), in Thin Solid Films, 99, (1983). The monolayer research has so far advanced according to possibilities offered by the 50 year-old LB monolayer deposition method, which established itself as the standard method presently employed in the preparation of planned monolayer assemblies. In principle, the LB procedure provides a versatile means for the direct handling of monomolecular films, enabling construction of planned layered structures with precise control of the layer sequence, interlayer spacings, and film thickness, down to submolecular dimensions. However, in practice it suffers from some drawbacks and inherent limitations, mainly due to the extensive use of mechanical manipulation in the film building process. This affects the stability, homogeneity, and final structure of the resulting built-up films. Much of the present research effort in this area is expended on the optimization of the LB deposition technique, and on the exploration of ways for improving the stability and tenacity of the films, mainly via polymerization of monomeric film components.
Ordered monolayers similar to those produced by the LB method may be prepared on solids by direct adsorption of appropriate molecules at appropriate solid-fluid interfaces. The study of these so-called oleophobic monolayers (not wetted by organic oils) was pioneered by Zisman and coworkers in the 1950s (W. C. Bigelow et al., J. Colloid Sci., 1, 513 (1946); O. Levine and W. A. Zisman, J. Phys. Chem., 61, 1068 (1957). Zisman's adsorption method is limited to the formation of films of one-monolayer only, which prevents oleophobic monolayers from being employed in the constructio of multilayer film structures resembling the built-up films obtained by the LB technique.